#!/usr/bin/python3
from sys import argv, exit

if(argv[1] == '-a' or argv[1] == '-m'):
    flag = argv[1]
    toadd = argv[2:]
else:
    flag = ""
    toadd = argv[1:]

try:
    toadd = [float(n) for n in toadd]
except:
    print("Problem parsing input.  Usage instructions follow")
    exit(1)

def product(lst):
    p = 1.0
    for n in lst:
        p *= n
    return p

if(flag == '-a'):
    print(sum(toadd)/len(toadd))
elif(flag == '-m'):
    print(product(toadd))
else:
    print(sum(toadd))